There is a conventional system in which a top sheet coated with microcapsules containing minute oil drop having a nucleophilic organic color former dissolved therein and a bottom sheet coated with an electrophilic developer are put one on the other with their coated surfaces facing each other and are used as a set at the time of recording. In this case, the pressure as externally applied at the time of recording ruptures the microcapsules on the top sheet and transfers the contents of the microcapsules to the surface of the bottom sheet to thereby form an image on the developer sheet.
However, the image formed on the developer sheet (bottom sheet) by such a conventional system has a very low weather durability, particularly, light resistivity to ultraviolet rays because the dye formed by the reaction of the nucelophilic organic color former with the electrophilic developer is easily decomposed by the ultraviolet rays. The light resistivity may be improved by including an ultraviolet-ray absorbent in the developer-coated layer, but this ultraviolet-ray absorbent is likely to hinder the color-forming reaction of the nucleophilic organic color former with the electrophilic developer on the developer sheet.